5AT here to stay? no CVT or dual clutch?

[greg_atlanta]

Can we expect the next Q (or M or G) to have something other than a 5 speed auto trans? Any chance of a new trans for existing M & G models?

Nissan is using CVT with 3.5 V-6 in several FWD/AWD models, G/skyline has CVT in Japan (RWD, smaller V-6), and new GT-R will have dual cluth transmission (but rear mounted).

I'd like to see highway mileage closer to 30 mpg for all of these models. Think that's possible without a major drop in engine displacement and/or total weight?

[qship96]

7 speed nissan transmission is on the way!

[Q45tech]

The early Q had a 4th gear of 0.694 x 3.538= 2.455372 yielding 2,000 rpm at 60 mph.

The experiments with the [lighter 3801 pound] 2002 Q of 2.764 diff with a 0.83 5th gear yielded a 2.294 ratio and 6% lower rpm at 60 mph........................drive one at 60 mph and see if you can stand even 120 rpm lower.

They tweaked the engine [smaller valves and cam] to try to build up torgue at <2,000 but were not very successful.

A rigorously enforced [burn violators car and driver] back to 55 mph top speed would go a long way in improving highway fleet average MPG.

Too many heavy safety and fancy gadgets.Who needs more than 4 speakers .................how did the 2008 M45 get heavier than the 1990 Q. and require a 3.36 x0.83= 2.7888 final ratio... 13.7% > rpm to haul the fatness!

New LS460 weighs 4244 pounds and needs a 8 speed to function:1st Gear 4.596 2nd Gear 2.724 3rd Gear 1.863 4th Gear 1.464 5th Gear 1.231 6th Gear 1.000 7th Gear 0.824 8th Gear 0.685

Final Drive 2.937

7th gear happens to be exactly the same as 4th in an early Q and 5th is the same as 3rd in early Q.

8th doesn't engage below 65 mph

All that proves is there is an optimum gear or a speed/rpm/weight on a car.

I'm sure when direct injection comes along on Q that they will use it to improve mpg by 7-11% [2 mpg on highway]............they are promising a 5.0 liter engine which should negate the DI gains but allow the new 7 speed to function [?].

There is a reason displacement is ANNUALLY taxed everywhere except North America as that is a true refelction of MPG.

[Jesda]

Speak for yourself. 6.0L Corvettes enjoy 26 mpg at cruise.

[maxnix]

A rigorously enforced [burn violators car and driver] back to 55 mph top speed would go a long way in improving highway fleet average MPG.

If this argument is followed to its logical conclusion, then we are better off if nothing is ever moved and no place is heated. Just wear more furs!

The productivity losses of artificial lower than necessary for safety speed limits is ignored. Time is indeed money, as is energy.
Modified by maxnix at 7:05 AM 11/26/2007

[maxnix]

Speak for yourself. 6.0L Corvettes enjoy 26 mpg at cruise.

That is because basically their design is a low rpm high torque truck engine.

Same approach Detroit took in the seventies with huge detuned V8 barely ticking over, but had enough torque to pull cars on the flat. Engines regularly blew if driven at 100 mph for a few minutes. GM couldn't even design the Vega four cyllinder head oil galleys to drain oil back to the cranckcase at high enough rate at high rpm to prevent bottom end from seizing.

[Q45tech]

Simply the weight of the lux vehicle that causes the low rpm lugging problem. the running out of torque bogging the engine down limiting the rpm and thus the mpg.

Put the Q engine in the Corvette and it should get close to GM mpg on highway because you could gear it to run 1500 instead of 2,000 rpm at 60 mph.

1500/2000= 0.75 so it should get 23 x 1.25 = 28.75 mpg.

The other things to consider is the weight of internal rotating components that act like a flywheel to reduce low rpm bog. I'll bet the GM pistons , rods and crank weigh more than the Q units.

[Jesda]

That is because basically their design is a low rpm high torque truck engine.

And thats why taxing based on displacement is STUPID.

[Q45tech]

Except that the amount of pollution is related to displacement just as the idle fuel consumption is.

Big bores pollute more due to colder cylinder walls and crevice volume.

[Jesda]

Except that the amount of pollution is related to displacement just as the idle fuel consumption is.

Big bores pollute more due to colder cylinder walls and crevice volume.

But it doesn't necessarily affect fuel economy, not in all cases. This is why, thank goodness, we live in a free society, and the EU is its own heap of socialist trash.